AbstractThe influence of free stream direction on mixed (natural and forced) convective heat transfer from a circular cylinder is investigated. The cylinder, which has an isothermal surface, is placed with its axis horizontal and normal to the oncoming flow. The free stream direction varies between the vertically upward (parallel flow) and the vertically downward (contraflow) directions. The investigation is based on the time integration of the unsteady, two‐dimensional equations of motion and energy until reaching steady conditions. The study is limited to Reynolds numbers up toRe= 40 and Grashoff numbers ofGr=Re2. The results are compared with the available experimental data and the agreement is satisfactor